NO2 products are regarded as perception products as they relate to gaining muscle. You get the perception that it´s working solely on the basis of the pump. The pump feel is a terrific tool to sell product, however a very poor way to judge muscle growth. A great analogy is a balloon filled with helium. For a period of time it appears to defy gravity and floats in air, however it´s only a matter of time before the balloon deflates and loses its magical powers. While NO2 products may not be the best choice for long term quality muscle gains, they certainly have value in the endurance market.